claimant; requester
A person who formally or officially requests or demands something, such as a service, right, or information.
The requester of information disclosure should fill out the prescribed form.
The claimant for insurance money must submit an accident report.
依頼者 is a client or person who entrusts a task to someone, whereas 要求者 focuses on the act of requesting or demanding something specific.
Compound of 要求 (request, demand) and 者 (person). The reading is standard on'yomi.