Need help setting up a search form for wordpress [duplicate]

I know you asked for no plugin suggestion but I thought I’d share the solution I commonly use for creating advanced search forms in WordPress.

http://wpadvancedsearch.com/

This is not a plugin but a PHP framework for building advanced search forms in WordPress. It has served me especially well with custom post types and creating search forms that filter results using custom meta values, taxonomies and more.

The framework enables you to set up a customized search form that displays result using variables passed from your search form to WP_Query.

You could use this framework either in your theme or in a plugin. Their documentation is also very good.

Hope this helps!

Herman