Process to search query from database

I am working on some custom software of employees system. For that I need to create a function which search from database fields on the basis of some specific fields. Like I want to put Phone no, name or address. user can put any information a little what he knows and can search on the basis of that with mysql like operator.

But I am confused on data flow how to filter empty values and how to create on the basis of that. can anybody guide me?