tricky customer

Translations
сложный клиент
He is a tricky customer to deal with when he gets angry.
С ним сложно иметь дело, когда он злится.
Definitions
A person who is difficult to deal with, often because they are clever, cunning, or unpredictable in their behavior or demands.
Words
customer

noun
клиент
tricky

adjective
хитрый