LONDON — When he was a boy, Oscar Murillo told his best friend he was moving to London, but his buddy refused to take him seriously: Their tight-knit community in southwestern Colombia was the sort of place families stayed for generations, where almost everybody worked at the candy factory that dominated the town’s economy. The news, however, was true. In the 1990s, the 11-year-old Oscar left La Paila, Colombia, and arrived in East London, where his parents took jobs as office cleaners. Speaking little English and having been displaced, he took refuge in drawing. These early scribblings pointed Mr. Murillo to painting, which in turn led to a multimedia art practice and, in 2019, to his winning the Turner Prize, one of the art world’s most prestigious honors. But the memories of La Paila, and of the succor he found in those early doodles, still inform his work, which now hangs in major museums around the world. His canvases, multilayered patchworks of color that can also include glued grime and supersize Spanish words, now fetch $300,000 or more at auction. “My work is a social detonator,” said the soft-spoken Mr. Murillo, a way for the son of working-class immigrant parents to blast through the barriers surrounding a social class that typically denies entry to people like him. “It’s a way to infiltrate the system.” While some might see a contradiction or even hypocrisy in an artist earning so much to send a socially conscious message, critics see it differently.