Entity Framework 6 Code First - Map Function Or StoredProc to primative type

Question

I am looking to implement something like the following"

string searchValue = "Jun";
var users = context.Users
             .Where(x => x.BirthDate.SomeWhackySqlFunction(searchTerm))
             .ToList();

where SomeWhackySqlFunction maps to a function or storedProc with in sql server that has 2 parameters:

• value: DateTime (in the sample code above it would be the value of birthDate).
• searchTerm: string

This is to get around limitations with EF , alternatively if I Could extend the DbFunctions or SqlFunctions class, this could also do the trick.