register adition.jar

a = LOAD 'TestCONTAINS-testFilteringCluster-input.txt' AS (id:int, grp:int, additional:int, referer:chararray);
b = FILTER a BY com.adition.pig.filtering.string.CONTAINS(referer, 'obama') OR com.adition.pig.filtering.string.CONTAINS(referer, 'praesident');

EXPLAIN b;

dump b;