Search for Custom Field with Custom Post Types

[admin]

There are tutorials that explain how to limit a search to a specific category.

My question is, is there a way to configure wordpress' search to, within a custom post type, search for a custom field value.

So for example, if I search for "hello", the results would come up with posts that have a certain custom field equal to "hello". The certain post would also be a certain custom post type.

Any help is appreciated.