He attended the Pontifical Gregorian University in Rome.
After his ordination, he served the Deanery of Szentgotthárd in the parish of Felsoszölnök and Apátistvánfalva, and was known for celebrating bilingual masses in Hungarian and Prekmurje Slovene.
In 2011, Merkli translated the work of Lojzer Kozar into Hungarian, and compiled a hymnal with content in the Prekmurje dialect and standard Slovene for the Hungarian Slovenes with Lojzer Kozar Jr.