ˌsocial ˈclimber noun [countable]
someone who tries to get accepted into a higher social class by becoming friendly with people who belong to that class – used in order to show disapproval

[TahlilGaran] Dictionary of Contemporary English ▲

social climber
someone who tries to join a higher social class, especially by becoming friends with people from that class.
He was a dedicated social climber and was at all the best parties.

[TahlilGaran] English Idioms Dictionary ▲

social climber
n. A person who tries to mix with rich or well-known people and be accepted by them as friends and equals.
People do not like Mrs. Brown very well; she is known as a social climber.
Social climbers are usually soon known and they are not accepted by those they run after.

[TahlilGaran] English Idioms Dictionary ▲