Search and Multisite

Not that I’m aware within WordPress’ native search, no. Instead, you’ll probably need to implement a custom search engine (in our case, we’ve implemented a Google CSE for use on our sites).

About the only way I can think of to try to accomplish this with the native WordPress search would be to implement Sitewide Tags (or similar aggregation plugin), then modify the search engine to search that site instead of the site currently being viewed.