formula linking "like" text
 

I have a workbook (Client Fees) with several sheets. Each sheet represents a
different client's auction fees (I sell on consignment on several sites). I
import my invoice each month from the auction sites and convert it to a
spreadsheet format. I need an external formula that will link the matching
text in the new invoice to the same text in the Client Fees workbook. I need
to eliminate having to put the client's names next to each entry in the
invoice, sort it and then add it to the corresponding Client Fees worksheet.
Hope this makes sense! Thanks in advance! Jennifer