noun
A person who requests a service or task, especially in professional contexts such as law, business, or investigation.
弁護士は依頼者の話を注意深く聞いた。
The lawyer listened carefully to the client's story.
探偵は依頼者から調査の依頼を受けた。
The detective received an investigation request from the client.
クライアント is a common loanword for 'client' in business and IT, often interchangeable with 依頼者 but more casual and broader in scope.
Compound of 依頼 (irai, 'request') + 者 (sha, 'person'). The reading is standard on'yomi.