searching a cell with a string of comma delimited values in excel

Use FILTERXML:

=IF(OR(ISNUMBER(SEARCH(FILTERXML("<a><b>"&substitute(INDEX(CODES, MATCH([@A], CODES[A], 0), MATCH("B", CODES[#Headers],0)),",","</b><b>")&"</b></a>","//b"),[@B]))), "NOK", "OK")

Make sure you change #Headers to your language if different than English

This will need to be confirmed with Ctrl-Shift-Enter instead of Enter when exiting edit mode in Excel 2013.