Answer by warren for Splunk Streamlined search for specific fields only

Use OR:

index=ndx sourcetype=srctp (fieldA="myval" OR fieldB="myval" OR fieldC="myval")

Parenthesis added for clarity/readability

from User warren – Stack Overflow https://stackoverflow.com/questions/67495862/splunk-streamlined-search-for-specific-fields-only/67496173#67496173
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