The standard is searching for whole words. If you need to search for part of a word you can use * (asterisk) as wildcard - searching for graph* will include results for both graphene or graphics.
You can use ? (question mark) to replace one character in a word - searching for Pe?er will include results for both Peter and Peder.
You can use both AND and OR in searches. As an example; searching for Human AND Capital will only find the publications with both of the words human and capital. Human OR Capital will find all publications with either the word human or capital.
Text in quotation marks will search for complete sentences. Using AND or OR within quotation marks will regard them as normal words. If you search for a specific person don't use quotation marks around the name.