[Typo3] 'No search' option controlling <meta name="robots" />

[Robert Markula]

In every page header there is an option called "No search".
I want this option to control the <meta name="robots" content="" /> meta 
tag. So when the 'no search' option is checked, in the HTML header <meta 
name="robots" content="" /> should be set to "none". If this option is 
not checked, the meta tag should be set to <meta name="robots" 
content="all" />.

How can I do this with TypoScript?

Ro