Klein is from the Philippines. As a trained sociologist, he is an experienced state planner and aid policy analyst. Klein worked on peace building efforts in broken communities fraught by decades-old armed conflict in the Philippines. His interest in medical anthropology led him to study the changes in the traditional health system of indigenous communities who were under the threat of displacement due to extractive mining activities. He completed a Master of Public Health as an Australian Awards Scholar at the Centre for Health Stewardship of the Australian National University. During his graduate studies, Klein embarked on the ethical analysis of health service delivery by looking into the structural relations between the national and local governments as principal health providers among the indigenous communities. He is currently an active member of the International Sociological Association and its Research Committee 28 for Social Stratification.