Currently it is impossible to do a search for text within a given issue. Part of what we're working on with the database is an index of items found in each magazine, but we're nowhere close to finishing that up, and due to real life stuff, I haven't had time to work on it for several months.
The Video Game History Foundation might be a help to you though. Their digital magazine library, while not as robust as our scan collection, does offer keyword search functionality for the issues they have on offer.
Also, if you tell us what you're looking for, other forum members might be able to point you in the right direction.