Final answer:
The logical operator used when specifying multiple criteria where at least one must be true for a record to be included is 'OR'. This operator broadens the search results by including any record where any criteria are met.
Step-by-step explanation:
When you want to specify criteria in multiple fields, and at least one of the criteria must be true for a record to be included in the results, the OR logical operator is used. The OR operator connects two or more similar concepts and broadens your search results, indicating to the search engine or database that any of the search terms can appear in the results. This is different from the AND operator, which narrows search results by telling the database to include all search terms in finding sources. The OR operator thus creates a larger set of results, as it includes any record where at least one of the search criteria is met.