Return nested fields in elastic search query

Very new to elastic search.
I have a data set that includes nested objects. I have a query with a bool should array that is created when I do a keyword search on a web app. By default, the field values in the nested objects are not returned in the response for this query - these fields are what I need access to. I can get them to return if I use a nested query but it seems no matter what I do, I influence the results of the query. For example, if I add a nested field in the bool should query, it returns ALL possible results regardless of the search keyword because every possible result has SOME value in this nested field. What's the best way to get nested fields in an elastic search response without influencing the response at all?

Example query:

"stored_fields": [
  "document_code",
  "filename"
],
"query": {
  "bool": {
    "should": [
      {
        "match": {
          "filename": "some filename"
        }
      }
    ]
  } 
}

this query will return ONLY the document that matches the exact document code - as it should - but the response does not include any of the nested fields that might be associated with the document.
i.e.

"total": {
  "value": 1
}
"hits": [
  {
    "fields": {
      "document_code": [
        "123456"
      ],
      "filename": [
        "some filename"
      ]
   }
]

I need the nested fields in the response as they would appear if I used this query:

"stored_fields": [
  "document_code",
  "filename"
],
"query": {
  "bool": {
    "should": [
      {
        "match": {
          "filename": "some filename"
        }
      },
      {
        "nested": {
          "path": "nested_fields",
          "query": {
            "match_all" {}
          },
          "inner_hits": {
            "stored_fields": [
              "nested_fields.field_one",
              "nested_fields.field_two
            ]
          }
        }
      }
    ]
  } 
}

which gives me a response that looks like this:

"total": {
  "value": 10000
},
"hits": [
  {
    "fields": {
      "document_code": [
        "123456"
      ],
      "filename": [
        "some filename"
      ]
   },
   "inner_hits": {
     "nested_fields": {
       "hits": {
         "total": 1
         "hits": [
           {
             "fields": {
               "nested_fields.field_one": [ "nested field one value" ],
               "nested_fields.field_two": [ "nested field two value" ]
             }
           } 
         ]
       }
     }
   },
   {
   .....and 10,000 additional hits that dont match the document code
   }
]

It's clear to me why I'm not getting the results that I need. I'm basically saying "give me results that match this document code OR have ANY nested field. Since they all have some value in this nested field, the query returns every single document. I just don't know how to get the response to contain the inner_hits values without matching for something. I've tried to replace the "match_all" in the nested query with match_none and that returns the correct results (the ONE and only document with that document code) with the nested_fields inner_hits but it's empty and I need the values.

Also note that in my actual application, there would be a bunch of other wildcards and matches to search for some keyword throughout different parts of the document.

In short, I'm not actually trying to filter the results based on the nested fields at all - I just need them in the response.

I imagine that the document has the field nested "nested_fields".

In this case, as you only need to display the nested field and the others, you would make the change below:

"stored_fields": [
  "document_code",
  "filename"
],

To

 "_source": {
    "includes": [
      "document_code",
      "filename",
      "nested_fields"
    ]
  },