The ArcCatalog Search dialog box is not optimal for finding objects that have ISO-style metadata. In general, it is only possible to find ISO metadata documents using a "Full Text" search. If you use ArcCatalog to search the contents of an ArcIMS Metadata Service you will also be able to find ISO metadata documents using geographic criteria. Searches can't be constrained to test the content of specific metadata elements unless you know the ISO XML element that contains the information you are looking for. In that instance, type the path to that XML element into the Metadata element text box on the Advanced tab.