Type for object with required key value pairs and additionally any other key value pairs

I am trying to declare an object which should have all keys of MyEnum with the value of type EnumValue and any other keys with string type value. Please see the example below.

enum MyEnum {
    A = 'A',
    B = 'B',
}

type EnumValue = {
    title: string;
    infoText: string;
};

type RequiredType = Record<MyEnum, EnumValue>;

const myObj = {
    A: { infoText: 'a', title: 'a title' },
    B: { infoText: 'b', title: 'b title' },
    someOtherKey: 'string value',
};

How to specify the type for myObj so it would be of type Record<MyEnum, EnumValue> as the required type (all enum values should be included as keys) and additionally accept Record<string, string> type?

Edit: also I would like to have autocompletion for all keys in that object. Is it possible by inferring properties from declared myObj?

You need to declare myObj as of type myObjType

 type myObjType = RequiredType & Record<string,string>;
     const myObj:myObjType = {A:{infoText:'a',title:'a title'},
                              B:{infoText:'b',title:'b title'},
                               someOtherKey:'string value',};