customization to start search w/o custom fields (Gallery 2.2.5)

hey,

I am trying to achive something particular but couldn´t figure it out checking the forums.

I use the custom filed for extended informations, which I want to be part of a possible advanced search, but which should *not be part of the initial seearch*.
so I want wo configure the search in a way, that initial search from the searchbox, *doesn´t search the custom fields*, but that this option remains for advanced search. so I do *not want to turn off the search integration for custom fields globally* (which I have found in the forums), but rather find a way to "uncheck" the option for search custom fields in the default search, leaving the user the option to check this option later, once he/she is in the advanced search interface.

any ideas, hints, hacks, tips and tricks appreciated!!