Find a cell with String value - complex

Col B has all the sub-strings that needs to be searched.
Col A has the full length strings that needs to be returned.

VLOOKUP is not the answer; neither is INDEX/MATCH combo - in my opinion.

Take a substring and match it against data in Col A and then return the Col A cell value. So sub-string in B6 exists in A3. So formula should return same value as A3 in C6. If sub-string is not found returning a "n/a" would be nice. (smile!)

Please help..

Thanks.
H-