You don't say which version you are on, so you may already have it. If your IN-A screen banner is Nov 22, 2004, you can do it, but it is not obvious. I thought there was a prior post explaining this, but I can't find it so here goes...
Go to IN-A. Do lookup in the item number screen. Doesn't matter what you search by at this point. When the list screen comes up, there is a search button in the lower right corner. Clicking this gives you 4 options:  
1. Item number substring
2. Description substring
3. 2nd description substring
4. Desc or 2nd desc substring
 
If you don't have this, you might want to consider updating. Lots of cool new tools have been added.

This search function is also available just about anywhere you do an Item Number Lookup (WO-A, SO-A, PO-A, etc).