Lemnaru started playing football as a goalkeeper at the age of eight at his home town team, Victoria Lehliu.
In 2003, due to salary issues, he refused to play for Politehnica Timișoara and he was suspended by the team owner, Claudio Zambon, for almost two years.
In January 2009 he was loaned to Astra Ploieşti and later that year Lemnaru was transferred by the second league team Universitatea Cluj.
He scored 16 goals for Universitatea Cluj in one and a half seasons and after the team promoted in Liga I, the striker was loaned to Pandurii Târgu Jiu.
[11] But this remained his only game for Steaua, and in September 2014 he was sold back to Universitatea Cluj where he signed a two-year deal.