Partiz, I'm afraid what you want done is just not possible. See:
https://support.google.com/webmasters/answer/66353?hl=en
Also, if you must have hidden text, then to somewhat minimize bad SEO effects, make a separate page with all the hidden text you want and in the source code of that page, include the following between <head>
and </head>
:
<meta name="ROBOTS" content="NOINDEX">
Also add the following to all anchor tags that link to your rendition of hidden text:
rel="nofollow"
Depending on how the hidden text is used, make sure users are aware of anything sneaky you do. For example, if your hidden text suddenly appears on a page in the middle of the page after looking at it for five seconds, then at least put a warning about it on the previous page the user looked at.
I'm not sure if anyone will have a better answer than what I can provide here, but the reality is, search engines don't like sneaky acts on websites.