No.
"Clients" originally referred to the relationship between a lawyer and the person he represents. It is commonly used these days where the relationship is very different, often I suspect to imply an unnecessary sense of self importance.
Really? Which part of depending on another for safety and protection is an "unnecessary sense of self-importance."
client - Dictionary definition and pronunciation - Yahoo! Education
cli·ent audio (klnt) KEY
NOUN:
1. The party for which professional services are rendered, as by an attorney.
2. A customer or patron: clients of the hotel.
3. A person using the services of a social services agency.
4. One that depends on the protection of another.
5. A client state.
6. Computer Science A computer or program that can download files for manipulation, run applications, or request application-based services from a file server.
ETYMOLOGY:
Middle English, from Old French, from Latin clins, client-, dependent, follower; see klei- in Indo-European roots
A customer need not pay to be a customer.
Perhaps your passengers do not depend on you for safety, or to protect them from harm. In general, however, the definition of pilot in command is the person to whom is entrusted the safe outcome of the flight. The duty of the pilot in command is to protect the aircraft and passengers from harm by operating professionally, safely, and within the constriction of the guidelines and regulations that govern the flight.
Most assuredly a passenger is a client.
Treating every passenger as a client, with respect, while protecting their safety is not an act of contempt, but a standard act of airmanship. A passenger, as your customer, should expect no less.
Customer - Wikipedia, the free encyclopedia
A customer (also known as a client, buyer, or purchaser) is usually used to refer to a current or potential buyer or user of the products of an individual or organization, called the supplier, seller, or vendor. This is typically through purchasing or renting goods or services. However, in certain contexts, the term customer also includes by extension any entity that uses or experiences the services of another. A customer may also be a viewer of the product or service that is being sold despite deciding not to buy them. The general distinction between a customer and a client is that a customer purchases products whereas a client purchases services.
Any passenger of mine is my client.