ORs in Arrays/Sumproduct are generally conducted by means of addition, eg:

=PERCENTILE(IF(((DATA!AW:AW="u")+(DATA!AW:AW="h"))*(Data!A:A=590),Data!AH:AH),0.4)
confirmed with CTRL + SHIFT + ENTER

Though in 2007 and beyond use of entire column references is permitted in Arrays it is not advised in terms of performance - restrict the ranges being processed whenever & wherever possible.