Searching for a particular person by specifying her name is one of the essential functions in online social networking services such as Facebook. So many times, however, one would like to find a person but what she knows is few social labels about the target, such as interests, skills, hometown, school, employment, etc. Assume each user is associated a set of social labels, we propose a novel search in online social network, Person-of-Interest (POI) Search, which aims to find a list of desired targets based on a set of user-specified query labels that depict the targets. We develop a greedy heuristic graph search algorithm, which finds the target who not only covers the query labels, but also either possesses better social interactions with peers or has higher social proximity towards the user. Experiments conducted on Facebook and Twitter datasets exhibit the satisfying accuracy and encourage more advanced efforts on POI search.