I found a way to do this, I changed in content.php the first part of the search part by the second part of the if-else. There should probably be an easier way, because now I have an if-else with twice the same code, but it works! If anybody has a better solution, please be free to share …
<?php if ( is_search() ) : ?>
<div class="entry-summary">
<?php the_excerpt(); ?>
</div><!-- .entry-summary -->
<?php else : ?>
<div class="entry-content">
<?php
the_content( __( 'Read more <span class="meta-nav">→</span>', 'twentyfourteen' ) );
wp_link_pages( array(
'before' => '<div class="page-links"><span class="page-links-title">' . __( 'Pages:', 'twentyfourteen' ) . '</span>',
'after' => '</div>',
'link_before' => '<span>',
'link_after' => '</span>',
) );
?>
</div><!-- .entry-content -->
<?php endif; ?>
is now :
<?php if ( is_search() ) : ?>
<div class="entry-summary">
<?php
the_content( __( 'Read more <span class="meta-nav">→</span>', 'twentyfourteen' ) );
wp_link_pages( array(
'before' => '<div class="page-links"><span class="page-links-title">' . __( 'Pages:', 'twentyfourteen' ) . '</span>',
'after' => '</div>',
'link_before' => '<span>',
'link_after' => '</span>',
) );
?>
</div><!-- .entry-summary -->
<?php else : ?>
<div class="entry-content">
<?php
the_content( __( 'Read more <span class="meta-nav">→</span>', 'twentyfourteen' ) );
wp_link_pages( array(
'before' => '<div class="page-links"><span class="page-links-title">' . __( 'Pages:', 'twentyfourteen' ) . '</span>',
'after' => '</div>',
'link_before' => '<span>',
'link_after' => '</span>',
) );
?>
</div><!-- .entry-content -->
<?php endif; ?>