I'd keep the IINN data in a separate fields, on for II and one for NN and use a calculation to produce the full REQMMDDYYIINN value if that field is even needed. Then searching out this data is much simpler as you can specify this criteria in the individual fields as well has having easier data entry tasks.
Using the exsiting field, I'm not sure if "REQ" represents a number or the specfic letters "REQ". Assuming that it is a number, *BN* should work to find your records. If it is the actual text, you should use: REQ*BN* as your search criteria.
Thanks Phil, *BN* was what I was looking for. Cheers!