With Whois Search you will do the search on a combination of 13 fields as default.If you want to do the search on other fields or want to know what the 13 fields are,please click Here. HERE
With Whois Search, your query string will be split into many terms based on whitespace by the internal analyzer, so the more terms input,the more records will be matched. Composite search on multiple fields can help you narrow down the results.
When you want to do a search on multiple fields, you may need boolean query.The boolean query can work by using the uppercase keywords "AND","OR" and "NOT".