There is actually nothing to fix: According to RFC 2849, DirectoryStrings containing non-ASCII chars,
like accented letters in your case, are displayed by ldapsearch encoded in base64.
Your string, once decoded, looks like
echo -n "Sm9zw6kg" | base64 -d
If you want them to be shown in readable form, either decode them, or use another LDAP client able to do decoding for you e.g. DSCC.