客に

to a customer; to customers, to a guest; to a visitor

→ 客
phrase Rare #22,601
to a customer; to customers 客 means “customer,” and に marks the person receiving or being addressed by an action.
JA: 店員は客に注文を尋ねた。
EN: The clerk asked the customer for their order.

君は、この店に来るあらゆる客に応対するだけでよい。

All you need to do is attend to every customer who comes into this store.

その八百屋は客にとても親切だ。

The greengrocer is very kind to his customers.

店の客にさ全部デタラメさ

I tell the customers at the shop nothing but lies.

— es[エス] (2001)

呼ぶのに暫くかかったぞ客に注意してなきゃすみません注文は?

It took you a while to call me. You need to pay attention to the customers. Sorry. What would you like to order?

— 人生スイッチ (2014)

phrase Rare #35,605
to a guest; to a visitor 客 means a guest or visitor, and に marks the person something is shown or given to.
JA: 彼女は客に赤ちゃんを見せた。
EN: She showed the baby to the guest.

この人たちは私の客にして、時間どおりにバーロウのところへ連れていくよ

I’ll make these people my customers and get them to Barlow on time.

じゃ客に言って

Then tell the customer.

— コーラス (2004)

夕方の客に出す分を釣ってくれればいい。

You just need to catch enough to serve the evening customers.

彼女は客に赤ちゃんを見せた。

She showed the baby to the guest.