In SharePoint 2007 Search, if you look for filename:"Budget" (with quotation marks), your search will return files named “Budget” such as "Budget.xlsx." A search for filename:budget (without quotation marks) will also return that file and files named "Budget_Current.xlsx" and "Budget_Next.xlsx." Only prefix matching is allowed in property searches, which means that you must have at least the first letter of the property value to complete the search.
You can also use wildcard characters in property searches. Wildcard searches include characters, such as “*”, which allows the search engine to substitute any number of characters and “?”, which allows the search engine to substitute any single character. Prefix matching is also required when you use wildcard characters. This means that you cannot insert wildcard characters in the middle of a property value such as W*ton or at the beginning of a property value such as *ington.
There are several approaches and tools out there that you can implement to add wildcard functionality into SharePoint, and most of them are without cost or obligation.
• Ramon Scott has posted a walkthough on how to configure wildcard searches yourself in your SharePoint environment. Be sure to check out the post's comments for additional information and a link to another post Ramon wrote on the subject - http://www.ramonscott.com/wordpress/?p=8
• Corey Roth has contributed a free wildcard search add-on for MOSS to CodePlex. As with all CodePlex applications its support is going to be limited, but it is a full 1.0 release of the component and it appears that Corey is still making updates to the project - http://www.codeplex.com/WildcardSearch
• Ontolica Search offers a free wildcard search add-on, with no restrictions on its use. I don't know what kind of support they offer it, and you will have to provide them marketing contact information in order to download it, just as an FYI - http://www.ontolica.com/Ontolica%20for%20MOSS%202007/Ontolica%20Wildcard.aspx/
• There's also another project on CodePlex you can check out (tip of the hat to Paul Galvin for finding this): http://www.codeplex.com/SPWildCardSearch/
Hope this helps you.