I was disappointed the other day when looking into the query that happens on WordPress searches. It seems that WordPress by default will only search for your keyword or phrase in the title and body of the post. Not in related category or other taxonomies and not in custom fields. This could pose to be a problem for some users and how they layout their content.
With the latest release of WordPress (3.x) offering both custom post types as well as custom taxonomies, there will be a lot of users wanting to take full advantage of these features along with custom fields to create unique content along side their blog and static page content. I have found a plugin that has been around for a while now, but with the latest revisions to the core of WordPress, will become more and more essential to people utilizing these new features.
If you want someone to be able to search your custom fields and other taxonomies though the built in WordPress search then you need the plugin called “Search Everything” by Dan Cameron of Sprout Venture. It’s a simple and well executed method of adding specific elements to the main WordPress search query.