Czech characters issue

Hello,

I'm having an issue when searching for keywords which contain czech characters such as ščřžýá. It doesn't find anything and after loading the page with results, the value I was looking for is displayed without the czech character. For instance Citranžkvat becomes Citrankvat. How to fix that please?

Thanks and regards!

The same problem with Polish characters: ą, ć, ę, ó, ł, ś, ź, ż.
For example, when I write the keyword "złoto" it will be changed in "zoto".
Cheers
Jan