Use "keyword" for an exact match search. egs: keyword = "admin" will get matches like: Admin Services Officer whereas keyword = admin will get matches like Admin Services Officer and Administrative Assistant.
Use +keyword to include a keyword and -keyword to exclude one. egs: keyword=+admin -assistant will get matches that contain the keyword admin AND not the keyword assistant.
Use keyword* to perform partial keyword search. egs: keyword=ad* will get matches that contain words beginning with ad.