Mysql REGEXP and Simple Search support for admin grid fields
Default: The default Magento text search - returns results that contain your search.
Simple: Allows "", "|" and "+". Searching for "Bra|Rob*son" will return Branca, Brita, Robinson, and Robertson results.
Regex: Full Mysql REGEXP support. Note - case sensitivity will not be supported unless your table collations are configured to support it.