WordPress custom Search

I have a form that collects a search term and a zip code. WordPress searches on these two terms and returns posts if either one appears in the content or the title of the post.

In addition, I also want posts returned if the search term is in the category of the post, which the site is currently not doing.

I’m thinking this is either a simple custom query or mySql statement, but I’m clueless on how to build it.

Please help, as it’s very important I get this done for the client as soon as possible.

Thanks to the community!