By default, the search function in WordPress searches only inside the post body not the comments. This in my opinion, is a serious limitation as comments are a valuable part of a blog. Also sometimes there are very useful comments in some posts which are helpful to a visitor.

WordPress plugin “Search Everything” attempts to eliminate this loss of functionality in WordPress.

This plugin enables the searching of Pages, Comments and more. No Hacking or modifications necessary, just upload the downloaded folder to your wp-content/plugins directory, make sure to activate the plugin and then configure it under Options > Search Everything.

Apart from comments, there are also options to search pages, attachments, drafts,  and custom fields (metadata). To install this plugin, just extract and upload to your plugins directory. Then go to your WordPress dashboard and activate the plugin.

Now in your dashboard, go to Options —-> Search Everything. Configure what pages you want the plugin to search and save your options. Now the search box in your blog will search inside comments and other things you set in your options.

Download Search Everything WordPress Plugin