I'm looking for a suitable word or expression, for someone who really loves to learn, search and read about new things (Technologies, science, economics, politics..), so that his passion is only to acquire more knowledge.
You might call such a person a:
Epistemophile: one who has a love of knowledge; specifically, excessive striving for or preoccupation with knowledge.
Philosophile: Similar, but more of an emphasis on learning and philosophy.
Sophophile: Similar, but with more of an emphasis on gaining wisdom.
A little further afield, some define the doctrine of gnosticism, and its members, the Gnostics, as subscribing to the:
belief that freedom derives solely from knowledge
Note that Gnosticism is variously defined, and this description is not even the most popular or common. However, as @JasperLocke points out, the more generic
Isn't connected to the Gnostic sect, and so doesn't have the religious/spiritural/mystical connotations.
Bonus, for the true epistemophile: one who is self-taught is called a autodidact.
Sources: Alpha Dictionary; Phronistery.info; Wikipedia
In business theory, the term "early adopter" is used to describe this type of person.
"In the diffusion of innovation theory, the minority group (comprising about 14 percent) of population which, after innovators, is first to try new ideas, processes, goods and services. Early adopters generally rely on their on intuition and vision, choose carefully, and have above-average education level. For any new product to be successful, it must attract innovators and early adopters, so that its acceptance or 'diffusion' moves on to early majority, late majority, and then on to laggards." http://www.businessdictionary.com/definition/early-adopters.html
In politics, fashion, art, and other fields, this person would be referred to as a "trendsetter".
A much older word that applies is a "philomath", a lover of learning. (from Greek "phil" meaning "loving" and "math" meaning "to learn")