He also holds Spanish citizenship, due to the many years spent in the country.
Having moved to Spain in his teens after being born in Chiclayo, Lambayeque Region, Merino played youth football with FC Barcelona (only one year) and RCD Mallorca. He made his senior debuts with the latter's reserves, in Segunda División B.
In January 2003, Merino joined Atlético Malagueño, being an important midfielder element as Málaga CF's B-team retained their newly acquired status in Segunda División, with the player having contributed with 20 games and five goals to the promotion (play-offs included). Subsequently, he moved to Switzerland and signed with Servette FC but, with the club facing bankruptcy, left in the following transfer window to Ciudad de Murcia – also in Spain's second level – alongside teammate João Paulo Daniel.
Merino was signed by Atromitos F.C. in January 2006, from fellow Superleague Greece side Akratitos FC. In February 2009, after two full seasons and two halves, he changed teams (and countries) again, joining U.S. Salernitana 1919 in Italy.
On 8 January 2011, Merino signed with Al-Nasr SC of the Kuwaiti Premier League, on loan from Salernitana. Less than one month after, however, he left the Asian club; according to the player, he decided to leave because he did not feel comfortable and had other objectives for his football career.
On 28 February 2011, Merino signed a half-season contract with Unión Comercio– at almost 29, this marked the first time he would be playing in the Peruvian Primera División. He stated the his main reason for joining was to earn a regular starting spot on the Peru national team.
Merino represented Spain at under-18 level, having already spent several years living in the country. He decided to play for Peru as a senior, earning his first and only cap on 7 June 2009 in a 1–2 home loss against Ecuador for the 2010 FIFA World Cup qualifiers.
Merino's younger brother, Iván, was also a footballer. A defender, he too represented Mallorca B and Salernitana.Juan Aurich
Peruvian Primera División: 2011