How can I overload the subsref method for the struct class?

I want to overload the subsref method for the struct class, to extend it with regular expression fieldname matching. I can create a subsref function in a @struct folder in my matlab path, which is indeed called when I use subsref(variable,... on a variable of class struct. But it is bypassed somehow when is use the common syntax variable.(... It looks like Matlab does not call the subsref method for structures, but handles it by some built-in mechanism. How can I achieve the "structVariable.fieldName" construction to call my own subsref method?