"Where can i search words in korean?"
Naver and Daum dictionaries are the best places I know to look up words and phrases.
You just need to learn the tricks of looking up the words efficiently.
Most importantly, you need to know the components of a given phrase, and after that knowing the dictionary form of a verb or adjective will help a lot. Unfortunately, a lot of Korean writings (especially on the Internet) contain bad spellings and word spacings to make it difficult to identify word boundaries.
For example, you may see "뭔일이야?" ("What's the matter" in street spelling).
The correct way to write it is "뭔 일이야?", and it is using the common contraction "뭔" for the more proper "무슨". So it is "무슨 일이야?", which has three parts: 무슨(what) 일(matter), and 이야 (conjugation of 이다 - is). If you know this, you can look up the three words and find the meaning right away.
Even if you don't, you can still type in 뭔일이야 and get the usage examples, which may not be what you're looking for, but you might still find what you want by following some clues in the examples.
First, you can select 국어 in the top banner instead of 영어/영영(English) since the Korean page will give you more information. For 뭔일이야, the first example includes "뭔 일" in bold type in the first example returned. From this you can guess 뭔 and 일 are separate words and look them up individually after changing it back to the English tab. And then you can look up the remaining 이야 similarly.
As you get better with a language, you also get savvy with the different ways of looking things up.