Bareiro started his football career in Club 12 de Octubre before moving to Club Libertad of his native country. He played for Paraguay at the 2004 Olympics, helping them to a silver medal by being the second top-scorer of the team behind José Cardozo. After the Olympics Bareiro moved to the Russian side FC Saturn and in 2007 he returned to Paraguay to play for Club Libertad. He later moved to Mexico to play with Leon on the Mexican Primera Division A, being the team topscorer.
In 2008 he moved to Tecos UAG, and in 2011 he moved to Cerro Porteño, he scored his first goal on 23 February 2011 against 3 de Febrero, in his 3rd soccer game with Cerro Porteño. He is currently playing for Olimpia.